A Double-blind Study Evaluating the Efficacy, Safety, and Tolerability of Zorevunersen in Patients With Dravet Syndrome

Key Inclusion Criteria:

1. Patients must be ≥2 and <18 years of age.

2. Patients must have a clinical diagnosis of DS confirmed by the Epilepsy StudyConsortium, Inc. (ESCI) and as defined by: Onset, prior to 12 months (inclusive, <13 months), of age, of recurrent focal withmotor signs, hemiclonic, or generalized tonic-clonic seizures. No other knownetiology causing clinical DS manifestations..

3. Patient must have a documented pathogenic, likely pathogenic variant, or variant ofuncertain significance in the sodium voltage-gated channel type 1 alpha subunit (SCN1A) gene. Patients who have SCN1A testing results of Negative (no variantsidentified) cannot be randomized.

4. Patient must experience the required number of major motor seizures during the 6-week Observation Period. Major motor seizure types included are Seizure typesincluded in counts are Hemiclonic, Focal with Motor Signs, Focal to BilateralTonic-Clonic, Generalized Tonic-Clonic, Tonic, Tonic/Atonic (Drop Attacks with fallor risk of fall), and Bilateral Clonic.

5. Patient must have used at least 2 prior interventions for seizures. These caninclude anti-seizure medications (ASMs), ketogenic diet and/or vagus nervestimulation (VNS) with either lack of adequate seizure control or discontinued dueto an AE(s). These interventions can be ongoing therapies.

6. Patient must be taking at least one ASM. Benzodiazepines or ASMs used on a standingbasis (i.e., not as needed [PRN]) for any indication will be considered an ASM.

7. Patients' maintenance ASMs and interventions for seizures (i.e., ketogenic diet orVNS), as well as any marijuana- or cannabinoid-based products, must have been stable (unless adjusted for weight) during the Baseline Period.

Key Exclusion Criteria:

1. Patient has documented variant in the SCN1A gene associated with gain-of-function

2. Patient is currently treated with a maintenance ASM acting primarily as a sodiumchannel blocker, including but not limited to phenytoin, carbamazepine,oxcarbazepine, lamotrigine, lacosamide, rufinamide, or cenobamate, given themechanism of action of zorevunersen.

3. Patient is currently treated with neuromodulation techniques (e.g., responsiveneurostimulation, deep brain stimulation, or transcranial magnetic stimulation),with the exception of VNS.

4. Patient has emergence of a new seizure type or reemergence of a past seizure type (seizure types that last occurred more than 12 months before Screening Visit A)during the Baseline Period, or has more than 1 hospitalization for seizures duringthe Baseline Period.